The present invention relates to a control apparatus of a motor driven power steering (MDPS) system, and more particularly, to a control apparatus of an MDPS system, which determines whether a fault has occurred in a hall sensor or encoder for sensing a position of a motor rotor, and controls a motor according to the determination result.
The MDPS system has a relatively small weight, occupies a relatively small space, and does not need an oil change, compared to an existing hydraulic power steering system. The MDPS system provides part of a steering torque which a driver needs to apply to a steering wheel during a steering operation, using an auxiliary power unit, thereby facilitating the steering operation.
That is, the MDPS system senses the driver's steering intention through a torque sensor connected to the steering wheel, and drives a motor to provide a proper force in consideration of the current vehicle velocity or the like, thereby assisting a steering force. When a vehicle is stopped/parked or driven at a low velocity, the MDPS system provides a large force to lessen the driver's force. When the vehicle is driven at a high velocity, the MDPS system provides only a small force to maintain the stability of vehicle body.
The related art of the present invention is disclosed in Korean Patent Publication No. 10-2015-0065986 published on Jun. 16, 2015 and entitled “Electronic control unit for detecting breakdown of motor position sensor”.
The conventional MDPS system cannot control the operation of the motor, when a fault has occurred in a hall sensor or encoder for sensing a position of the motor rotor. Thus, the MDPS system may not be normally operated either.
When a fault occurs in the hall sensor or encoder while the vehicle is driven, the MDPS system cannot normally assist a steering force. In this case, the vehicle may be exposed to the danger of an accident. Therefore, there is a demand for a system capable of determining whether a fault has occurred in the hall sensor or the encoder, and normally controlling the operation of the motor even though a fault has occurred in the hall sensor and the encoder.